From: Li Zefan <lizf@cn.fujitsu.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>,
Neil Horman <nhorman@tuxdriver.com>,
Herbert Xu <herbert@gondor.hengli.com.au>
Subject: Re: [PATCH 6/6] cls_cgroup: remove redundant rcu_read_lock/unlock
Date: Wed, 01 Feb 2012 15:20:00 +0800 [thread overview]
Message-ID: <4F28E7A0.6000309@cn.fujitsu.com> (raw)
In-Reply-To: <1328080039.22641.2.camel@edumazet-laptop>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index 213c856..c0bab23 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -1160,9 +1160,7 @@ void sock_update_classid(struct sock *sk)
>> {
>> u32 classid;
>>
>> - rcu_read_lock(); /* doing current task, which cannot vanish. */
>> classid = task_cls_classid(current);
>> - rcu_read_unlock();
>> if (classid && classid != sk->sk_classid)
>> sk->sk_classid = classid;
>
> Yes, this seems fine.
>
> Then, I wonder why we do the "if (classid && classid != sk->sk_classid)"
>
> before the :
>
> sk->sk_classid = classid;
>
> This seems unnecessary checks.
>
I was wondering about this too. He who added this may provide us with an
answer.
next prev parent reply other threads:[~2012-02-01 7:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 6:55 [PATCH 1/6] netprio_cgroup: fix an off-by-one bug Li Zefan
2012-02-01 6:55 ` [PATCH 2/6] netprio_cgroup: don't allocate prio table when a device is registered Li Zefan
2012-02-01 6:55 ` [PATCH 3/6] netprio_cgroup: fix wrong memory access when NETPRIO_CGROUP=m Li Zefan
2012-02-01 6:56 ` [PATCH 4/6] netprio_cgroup: use IS_ENABLED() and family Li Zefan
2012-02-01 6:59 ` David Miller
2012-02-01 7:06 ` Li Zefan
2012-02-01 7:07 ` David Miller
2012-02-01 7:22 ` Li Zefan
2012-02-01 12:02 ` Neil Horman
2012-02-01 6:56 ` [PATCH 5/6] cls_cgroup: " Li Zefan
2012-02-01 6:56 ` [PATCH 6/6] cls_cgroup: remove redundant rcu_read_lock/unlock Li Zefan
2012-02-01 7:07 ` Eric Dumazet
2012-02-01 7:10 ` David Miller
2012-02-01 7:20 ` Li Zefan [this message]
2012-02-01 7:23 ` Herbert Xu
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